<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
     html, body {
      height: 100%;
    }
    .container {
      height: 100%;
      position: relative;
    }
    .left{
      position: absolute;
      background-color: yellow;
      width: 200px;
      height: 100%;
      left: 0;
      top: 0;
    }
    .right {
      position: absolute;
      width: 200px;
      height: 100%;
      background-color: blue;
      top: 0;
      right: 0;
    }
    .mid {
      margin: 0 200px;
      height: 100%;
      background-color: red;
    }
  </style>
</head>
<body>
  <div class="container">
    <div class="left"></div>
    <div class="right"></div>
    <div class="mid"></div>
  </div>
</body>
</html>